(1) First, we encode relation instances in \(\mathcal {D}^\ell \)  and \(\mathcal {D}^u\)  using the entity pair encoder implemented as the pretrained BERT [1]}, which takes relation instances \(\lbrace s_i^\ell \rbrace _{i=1,...,N}\) , and \(\lbrace s_j^u\rbrace _{j=1,...,M}\) , as input, and output relation representation \(\mathbf {h_i^\ell }\) , \(\mathbf {h_j^u}\) . However, high-dimensional \(\mathbf {h}\)  can encode a mixture of various aspects of linguistic features and the derived clusters from \(\mathbf {h}\)  cannot explicit align with desired relational classes.
